How to calculate voltage drop

[MBD115]

My needs are about as humble as my humble drawing I'm trying to attach to this reply.

In my drawing you can see my setup. I wish to simply be able to change the 200k resistor to another value and "know" what the voltage will be on the tube. I now know after posting here that there is no easy formula to figure this, so my use of a variable resistor will work for my humble purposes. lol

The single resistor i'm interested in is marked on my drawing and the voltage on the tube is also labeled, with the stock setup.

Thanks again for all the replies. lol
I'm sorry I'm so dumb. This stuff is very hard to understand. lol

[sunnydaze]

Hi MBD,

This is pretty confusing to me too but wouldn't let it stop me from trying to make change in the circuit/tone. I guess Stanz a pretty smart guy, so I plugged some numbers in the spreadsheet he posted until the result was pretty close to the readings you provided earlier. (- thanks Stanz ):
Voltage In R1 R2 R3...R10
250 100,000 21,000 21,000

V1 V2 V3
163 145 127


Put your supply voltage of 250v, in cell b2 (below "Voltage In") and put 21,000 under all of the other resistor values (R2, R3...R10). Now toggle the resistor value under the R1 - hopefully, it will guess pretty close to the actual readings so you can try different values until you get the desired result.

Anyway, Not sure if it will be close at other resistor values, but it comes pretty close to the three readings you posted. FYI>I usually just use jumper wires and try different values until I get what I need, but if using this file a guessing tool works, will save some time and allow for more creativity.

sunnydaze

[MBD115]

So far I've just be using a hard resistor and a variable resistor together to find the resistance I want to use. It is quick that way I guess. lol

I just wanted to learn a better way, and I also wanted to learn this so it would help me understand other amp schematics a little better.

I'll try the spread sheet. lol

Thanks!!!